ORTOLANI F. & PAGLIUCA S.
Evoluzione morfostrutturale del margine orientale dell’Appennino meridionale tra il Molise e la Basilicata durante il Plio – Pleistocene e rapporti con la sismicità –Morphostructural evolution of the eastern margin of the Southern Apennines between Molise and Basilicata during the Plio-Quaternary. Relationship with seismicity
Pages 223-234
Abstract
This study investigates th e eastern sec tor of th e Southern Apennin es between Molise and Basilicata on the base of re sidual paleosur – face s findings lying at diff erent ele vat ions (from approximately 600 m to 1000 m] . Thi s sector is cha racterized by a high seismicity connected wit h Plio-Quaternary compressive tectonics due to crus tal deformations. Plio-Pleistocenic terrigenou s marine deposits, resting unconformably over the Mesozoi c and Pliocen ic deformed terrains of th e cha in, are present along this sector (Acerenza, Calvello, S. Arcangelo). Pleistocenic cont inent al f1uvio-lacustrine basins (Boiano-Sepi no, Benevento, Caudina Valley, Serino, Montella, Lioni, Baragiano, high Meland ro-Agri rivers valley, Mercure) and volcanic deposit s are also pre sent. The pa leosurface cuts unconformably all the terrains dated from th e Mesozoic to the Early Pleistocene and fossilizes the Mio ceni c and Plioceni c tecton ic pha ses. Moreover th e top surface is fossilized by th e Vulture volcan ic rocks , d ated from 0.8 to 0.5 m./y . The paleosur face is characteri zed by a not deeply excavated hydrographic drainage not connected with fault slopes which are strongly contro lled by high morphodynamics due to fluvia l and mass erosion . Morphologica l, stratigraphical and str uctural st udie s permit to explain the origin and significance of the summit paleosurface and seismicity , by reconstructing the stages of morphorecronic evoluti on during the Plio-Quaternary pha ses in the geodynamic framework of th e eastern sector. It has been not iced that th e elevat ion of the studied area was pro ximal to the Plei stocene shor eline, therefore the regional paleosurface was prevalently formed by marine abrasion and partially by subacrc al eros ion, coincid ently wit h pro bable periodic emer sions during th e Early-Middle Plei stocen e. An upward ri se followed by th e dislocation of the summi t paleosurface occured duri ng th e Early-Middle Pleistocene phases successively fossilized by the Vulture volcani c rocks. The fast rise and the tectonic di slocation s causing th e break up of the paleosurface have mod ified th e fluvial drain age and determined an act ive slope morphodynamics in argillaceous terrains. The dislocatio n of the abrasion marine paleosurfa ce caused the development of slopes and hidrograph ie drainages at pre sent more unbalanced. The seismici ty of the studied area is connected with the seismoge net ic struc tures boundering the west ern and eastern margin s of thi s secto r deformed by recent crustal compressive tectonics.